Thread controller for sewing machines



Oct. 10, 1950 F. F. ZEIER 2,525,038

THREAD CONTROLLER FOR SEWING MACHINES Filed March 19, 1948 2Sheets-Sheet 1 Oct. 10, 1950 F. F. ZEIEB 2.52 88 THREAD CONTI KOLLER FORSEWING MACHINES Filed March 19, 1948 2 Sheets-Sheet 2 1 u" L 52 3/ 35 T-l3 3 46 M 38 45 a? #8 47 mum INVEN TOE EEDEE/CKF ZEIEB v WITNESS B)ATTOEN TY Patented a. 10, 1950 THREAD CONTROLLER FOR SEWING MACHINESFrederick F. 1Zeier, Stratfield, Conm, assignor .to The SingerManufacturingflompany, Elizabeth, N. 3., a corporation of New JerseyApplication March 19, 1948, SerialNo. 15,80'6,

7 Claims. 1

This invention relates to sewing machines and more particularly to athread-controller adapted for use in a sewing machine of the typedisclosed in my copending application Serial No.. 15,805, filed March19, 1948. T

The invention has for an object to provide a improved thread-controllerwhich is conveniently accessible for threading.

Another object of the invention is to provide a thread-controllerparticularly adapted for a needle-feed chain-stitch machine in which theamount of looper travel is small compared to the amount of needletravel, the small looper travel making it desirable to have an efficient and accurate control of the looper-thread in order to insure theproper formation of the usual thread-triangle for entrance by theneedle.

The invention also aims to provide a threadcontroller which isadjustable to control its effect on the looper-thread during thecritical portions of the stitch-forming cycle, and to control its eifecton pulling off thread from the source of pply.

The foregoing and other objects and advantages of the invention willbest be understood from the following description of an illustrativeembodiment thereof shown in the accompanying drawings, in which:

Fig. 1 is a leftside elevation, partly broken away; of a substantiallycomplete feed-off-thearm sewing machine embodying the invention.

Fig.2 is a top plan view of a'section ofthe laterally extending arm ofthe machine-frame with a portion thereof broken away to illustratetheactuating devices for the rock-shaftcarrying the thread-controller.

Fig. 3' is a top plan'view similar 'to'FigsZ, and

"showing the thread-controller at the beginning of its thread take-upstroke. "Fig. i is a top plan view similar to Fig. 3,'but showing thethread-controller at the end of its Ithread take-up stroke, this viewalso illustrating the usual tension devices through which the threadtravels .prior .to entering the thread-con- .troller.

- Figifiis a perspective view with the cover-plate Referring more indetail tojthe -.drawings, the

.improved thread-controller is shown as embodied the looper includes aframe comprising a standard In of a bracket-arm terminating in anoverhanging head i l. Preferably integral with the front side of thestandard I 8 is the work-arm casting including an upper forwardlyprojecting arm l2, a laterally extending arm [3, and a verticallydepending arm I4 carrying a horizontal work-supporting arm 15 disposedso that its free end underlies the head ll The stitch-forming mechanismof the present machine comprises a thread-carrying needle l6 carried bythe lower end of a needle-bar l'l supported in said head H for endwisereciprocatory work-penetrating and sidewise vibratory workfeedingmovements. Cooperating with the needle 16 in the formation of two-threadchain-stitches is a thread-carrying looper 18 mounted upon alooper-carrying. bar l9 extending endwise ofsaid work-supporting arm I5.Assisting the needle and looper in stitch-formation is a movablespreader 2!] which is actuated to swing transversely of the path oftravel of the looper to engage and distendthe looper-thread to form theusual triangle with the previous'needle-threadloop for entrance by thedescending needle. Supplementing the needle H5 in feeding the workendwise of the work-supporting arm I5, is a lower four-motion feed-dog21 which is apertured in theusual manner to receive and back-up theneedle 5 during the work-feeding movement of the needle. Opposed to thefeed-dog 2! is the usual presser-foot 22 carried on the lower end of aspring-biased presser-bar 23 endwise slidably journaled in the head II.

As clearly shown and described in my copending application referred toabove, the looper l8 derives its endwise loop-seizing and -sheddingmovements and its sidewise needle-avoiding movements from mechanismdisposed within the vertically depending arm 14. This mechanism includesan actuating rock-shaft 24 journaled in bearing bushings 25 and 26 fixedin the top and bottom walls of the arm [4. v The shaft 24 isoperlatively connected at its lower end, by suitable means, to thelooper-bar l9 and has clamped to it adjacent its .upper end a rock-arm21 (Fig. 2) which is connected by a short pitman 28 to .a crank 29'formed on a rotary counter-shaft 30 journaled in the laterally extendingarm l3. Rotation of the crank 29 will effect an oscillation of.therock-shaft 24, which in turn will impart an endwise movement to thelooper-bar l9giving to 18 its loop-seizing and -shedding strokes. g

In chain-stitch sewing machines it is preferable to operate thelooper-thread controlling means from the looper-actuating mechanism inorder that exact timing between the looper and the thread-controller canbe conveniently obtained. To that end, the present thread-controller isadapted to be fastened on the exposed upper end of the looper-actuatingrock-shaft 24. Referring to Fig. 1, it will be seen that the means forsecuring the thread-controller on the rockshaft 24 includes a pair ofopposed clamp-jaws in the form of a thrust-washer 3| and a clamp-disk32. Extending through alined apertures in the clamp-disk 32 andthrust-washer 3| is a clampscrew 33 threaded into the tapped end of therock-shaft 24. Secured between the clamp-jaws 3| and 32 are a pair ofthread-engaging members 34 and 35, each of which is adapted to beendwise adjusted relative to the axis of the rock-shaft 24 by looseningthe clamp-screw 33. It will be understood that when the clamp-screw 33is loose, the clamp-disk 32 also can be angularly or circularly adjustedabout the axis'of the shaft 24. The thread-engaging member 34, which isthe shorter of the two members, is bent upwardly at its free end toprovide a vertically disposed thread-engaging limb 33 adapted to contactthe looper-thread T passing between a stationary thread-guide 3? and theupper end of a threadguiding device 38 secured in a channel 39 formed inthe outer wall of depending arm Id. The longer thread-engaging member isalso bent upwardly at its free end to provide a thread-engaging limb 40adapted to contact the looperthread T passing between a stationarythreadguide 4| and the thread-guide 31, the upper end of the limb 40terminating in a reve rsely bent tail 42 which overhangs thelooper-thread or threads and prevents them from sliding off the upperend of the thread-engaging limb 43' during the operation thereof.

The two stationary thread-guides 31 and 4| are adjustably secured bymeans of the screws 43 and 44 upon a supporting angle-bracket 45 whichis secured to the side wall of the depending arm I3 by the screws 46threaded into said arm. A suitable swing-up guardor cover-plate 47 ishinged to the angle-bracket 45 and when the cover-plate is in itslowered or closed position, as shown in Fig. l, the cover-plate servesto guard the operator from inadvertently contacting the rapidly movingtake-up arms 34 and 35.

Operation.

When the looper thread-controller is at the beginning of its take-upstroke, which position is illustrated in Fig. 3, the looper I8 isadvancing in its loop-seizing stroke endwise of the worksupporting armI5 in a direction toward the depending arm l l. During this stroke ofthe looper, slack looper-thread is produced adjacent the looper, and toabsorb this slack thread and maintain an accurate control on thelooper-thread, the thread-engaging member 34 is caused to swing from theposition shown in Fig. 3 to that shown in Fig. 4. In moving to theposition shown in Fig. 4, a bight is formed in the looper-thread Tbetween the thread-guide 3'! and the upper end of the thread-guidingdevice 38, the thread forming the bight being drawn back from thatportion of the thread leading to' the looper. By effecting the properrelative adjustment between the thread-engaging member 34 and thethreadguide 31, the looper-thread is so controlled that during theentire loop-seizing stroke of the looper I8 and while it is dwelling atthe end of its loopseizing stroke, the looper-thread is heldsufficiently taut that it is maintained in position to be unerringlyseized by the spreader 20 as the latter moves transversely of the looperto spread the thread-triangle for entrance by the descending needle.

In chain-stitch machines it is customary to provide means for drawingthread from the supply during each stitch-forming cycle, which thread isto be used in the subsequent stitchforming cycle. The thread-engagingmember 35 of the present device is provided for that purpose. Inoperation, the thread-engaging arm 35 swings between the two stationarythread-guides 7 and 4 I, forming a bight in the thread as shown in Fig.4. The thread forming the bight is pulled from the supply through theusual tension device 43 which i used to properly tension the thread inits passage to the looper. It will be observed in Fig. 3 that thevertical limb 40 of the member 35 is spaced from the looper-thread TThis is purposely done so that the thread pull-oil action will occuronly during the latter part of the active stroke of the thread-engagingarm 35.

From the foregoing, it will be understood that during the initialportion of the active stroke of the thread-controller, only one of thethread-engaging members, namely, member 34, contacts the looper-thread Tand not until all the lost motion between the thread-engaging member 35and the looper-thread is taken up, do both of the thread-engagingmembers 34 and 35 operate on the looper-thread simultaneously. As shownin Fig. 4, at the end of the active stroke of the two thread-engagingmembers 34 and 35, member 34 cooperating with the fixed thread-guide 3'!forces the looper-thread to undergo a sharp bend about the thread-guide31 which results in a snubbing action on the looper-thread and preventsany accidental movement of the thread toward the looper. When thesnubbing action on the thread occur it is at a critical time in thestitch-forming cycle when the spreader is operating to distend thelooper-thread limb of the thread-triangle. The snubbing action on thethread at this time is desirable because the looper-thread is therebyaccurately controlled and maintained elevated within the range of actionof the spreader device.

Having thus set forth the nature of the invention, what I claim hereinis:

1. In combination with a threaded reciprocatory needle and acomplemental thread-carrying looper, looper-operating mechanismincluding an actuating rock-shaft, of a thread-controlling mechanismincluding spaced thread guides through which the looper-thread passes,and movable thread-engaging members connected directly to said actuatingshaft and disposed so that one of said thread-engaging members operatesbetween the spaced thread-guides and the other operates outside thefield between said thread-guides.

2. A sewing machine having, a frame including an overhanging head, awork-supporting arm, and a depending arm carrying said work-supportingarm, an endwise reciprocatory needle carried by said head, athread-carrying looper supported by said work-supporting arm, mechanismfor operating said looper including an actuating shaft journaled in saiddepending arm and having one of its end-portions exposed, spacedthread-guides mounted on said depending arm, anda'thread-engaging'device mounted on the exposed end-portion of saidactuating shaft and ing shaft journaled in said frame, and athreadcontrolling mechanism including spaced threadguides, a pair ofmovable thread-engaging members disposed to contact the looper-threadadjacent said thread-guides, andaclamp device for securing saidthread-engaging members to said actuating shaft, said clamp deviceproviding for adjustment .of said members endwise of themselves andcircularly about the longitudinal axis of the actuating shaft.

4. In combination with stitch-forming devices including a threadedreciprocatory needle and a complemental thread-carrying looper,operating means for one of said stitch-forming devices ineluding anactuating rock-shaft, of a threadcontrolling mechanism including spacedthreadguides, and a pair of oscillatory thread-engaging membersconnected directly to said actuating shaft and disposed to operate uponthe thread adjacent said thread-guides, said thread-engaging membersbeing relatively arranged so that one is acting on the thread during agreater portion of its oscillation than is the other threadengagingmember.

5. A sewing machine having, a frame including an overhanging head and aWork-arm portion including a laterally extending arm, a depending armcarried by said laterally extending arm, and a work-supporting armcarried by said depending arm, an endwise reciprocatory needle carriedby said head, a thread-carrying looper supported by said Work-supportingarm, mechanism for actuating said looper including an actuating shaftjournaled in said depending arm lengthwise thereof and having its upperend-portion exposed at the top of the laterally extending arm, spacedNumber thread-guides, anda thread-engaging device mounted on the exposedend-portion of said actuating shaft and arranged to contact the threadadjacent said thread-guides.

6. Thread-controlling mechanism for sewing machines, comprising, athread-tension device, spaced thread-guides disposed to successivelydirect a thread leading from said tension-device, a

thread pull-off member having its I effective thread-engaging path ofmovement between said thread-guides, a thread take-up member having itseffective thread-engaging path of movement at the side of saidthread-guides remote from said tension-device, means for vibrating saidpull-off and take-up members about a common axis, and means providingfor relative adjustment of-said members radially of said axis.

7. In combination with stitch-forming devices including a threadedreciprocatory needle and a complemental thread-carrying looper,operating means for one of said stitch-forming devices including anactuating rock-shaft, of a threadcontrolling mechanism including spacedthreadguides, and a pair of movable thread-engaging members connecteddirectly to said actuating shaft and disposed to operate upon the threadadjacent said thread-guides, one of said threadguides and one of saidthread-engaging members being relatively arranged so that in one extremeposition of movement of said thread-engaging member the thread issnubbed between said member and said thread-guide and therebyeffectively locked against accidental movement.

, FREDERICK F. ZEIER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date 2,332,932 Riviere Oct. 26, 1943

